Proximity switch assembly having pliable surface and depression

ABSTRACT

A proximity switch assembly and method for detecting activation of a proximity switch assembly is provided. The assembly includes a plurality of proximity switches each having a proximity sensor providing a sense activation field and control circuitry processing the activation field of each proximity switch to sense activation. A pliable material overlays the proximity sensors. A depression is formed in a substrate between the pliable material and the sensor. A groove may extend into the substrate between adjacent proximity switches. The pliable material may further include an elevated portion.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation-in-part of U.S. patent applicationSer. No. 14/284,659, filed on May 22, 2014, entitled “PLIABLE PROXIMITYSWITCH ASSEMBLY AND ACTIVATION METHOD,” which is a continuation-in-partof U.S. patent application Ser. No. 14/168,614, filed on Jan. 30, 2014,entitled “PROXIMITY SWITCH ASSEMBLY AND ACTIVATION METHOD HAVING VIRTUALBUTTON MODE,” which is a continuation-in-part of U.S. patent applicationSer. No. 13/444,393, filed on Apr. 11, 2012, entitled “PROXIMITY SWITCHASSEMBLY AND ACTIVATION METHOD WITH EXPLORATION MODE.” Theaforementioned related applications are hereby incorporated byreference.

FIELD OF THE INVENTION

The present invention generally relates to switches, and moreparticularly relates to proximity switches having an enhanceddetermination of switch activation.

BACKGROUND OF THE INVENTION

Automotive vehicles are typically equipped with various user actuatableswitches, such as switches for operating devices including poweredwindows, headlights, windshield wipers, moonroofs or sunroofs, interiorlighting, radio and infotainment devices, and various other devices.Generally, these types of switches need to be actuated by a user inorder to activate or deactivate a device or perform some type of controlfunction. Proximity switches, such as capacitive switches, employ one ormore proximity sensors to generate a sense activation field and sensechanges to the activation field indicative of user actuation of theswitch, typically caused by a user's finger in close proximity orcontact with the sensor. Capacitive switches are typically configured todetect user actuation of the switch based on comparison of the senseactivation field to a threshold.

Switch assemblies often employ a plurality of capacitive switches inclose proximity to one another and generally require that a user selecta single desired capacitive switch to perform the intended operation. Insome applications, such as use in an automobile, the driver of thevehicle has limited ability to view the switches due to driverdistraction. In such applications, it is desirable to allow the user toexplore the switch assembly for a specific button while avoiding apremature determination of switch activation. Thus, it is desirable todiscriminate whether the user intends to activate a switch, or is simplyexploring for a specific switch button while focusing on a higherpriority task, such as driving, or has no intent to activate a switch.Accordingly, it is desirable to provide for a proximity switcharrangement which enhances the use of proximity switches by a person,such as a driver of a vehicle.

SUMMARY OF THE INVENTION

According to one aspect of the present invention, a proximity switchassembly is provided. The proximity switch assembly includes a rigidsubstrate having top and bottom surfaces, a proximity sensor disposed onthe substrate, and a pliable material disposed on the top surface of thesubstrate. The proximity switch assembly also includes a depressionwithin the top surface of the substrate in a region between the pliablematerial and the proxy sensor. The depression is larger than theproximity sensor.

According to another aspect of the present invention, a vehicleproximity switch assembly is provided. The vehicle proximity switchassembly includes a rigid substrate having first and second surfaces, aproximity sensor disposed on the first surface of the substrate, and apliable material disposed on the second surface of the substrate. Thevehicle proximity switch assembly also includes a depression forming anair gap within the second surface of the substrate in a region betweenthe pliable material and the proximity sensor. The depression is longerthan the proximity sensor.

These and other aspects, objects, and features of the present inventionwill be understood and appreciated by those skilled in the art uponstudying the following specification, claims, and appended drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

In the drawings:

FIG. 1 is a perspective view of a passenger compartment of an automotivevehicle having an overhead console employing a proximity switchassembly, according to one embodiment;

FIG. 2 is an enlarged view of the overhead console and proximity switchassembly shown in FIG. 1;

FIG. 3 is an enlarged cross-sectional view taken through line III-III inFIG. 2 showing an array of proximity switches in relation to a user'sfinger;

FIG. 4 is a schematic diagram of a capacitive sensor employed in each ofthe capacitive switches shown in FIG. 3;

FIG. 5 is a block diagram illustrating the proximity switch assembly,according to one embodiment;

FIG. 6 is a graph illustrating the signal count for one channelassociated with a capacitive sensor showing an activation motionprofile;

FIG. 7 is a graph illustrating the signal count for two channelsassociated with the capacitive sensors showing a slidingexploration/hunting motion profile;

FIG. 8 is a graph illustrating the signal count for a signal channelassociated with the capacitive sensors showing a slow activation motionprofile;

FIG. 9 is a graph illustrating the signal count for two channelsassociated with the capacitive sensors showing a fast slidingexploration/hunting motion profile;

FIG. 10 is a graph illustrating the signal count for three channelsassociated with the capacitive sensors in an exploration/hunting modeillustrating a stable press activation at the peak, according to oneembodiment;

FIG. 11 is a graph illustrating the signal count for three channelsassociated with the capacitive sensors in an exploration/hunting modeillustrating stable press activation on signal descent below the peak,according to another embodiment;

FIG. 12 is a graph illustrating the signal count for three channelsassociated with the capacitive sensors in an exploration/hunting modeillustrating increased stable pressure on a pad to activate a switch,according to a further embodiment;

FIG. 13 is a graph illustrating the signal count for three channelsassociated with the capacitive sensors in an exploration mode andselection of a pad based on increased stable pressure, according to afurther embodiment;

FIG. 14 is a state diagram illustrating five states of the capacitiveswitch assembly implemented with a state machine, according to oneembodiment;

FIG. 15 is a flow diagram illustrating a routine for executing a methodof activating a switch of the switch assembly, according to oneembodiment;

FIG. 16 is a flow diagram illustrating the processing of the switchactivation and switch release;

FIG. 17 is a flow diagram illustrating logic for switching between theswitch none and switch active states;

FIG. 18 is a flow diagram illustrating logic for switching from theactive switch state to the switch none or switch threshold state;

FIG. 19 is a flow diagram illustrating a routine for switching betweenthe switch threshold and switch hunting states;

FIG. 20 is a flow diagram illustrating a virtual button methodimplementing the switch hunting state;

FIG. 21 is a graph illustrating the signal count for a channelassociated with a capacitive sensor having an exploration mode and avirtual button mode for activating a switch, according to a furtherembodiment;

FIG. 22 is a graph illustrating the signal count for the virtual buttonmode in which an activation is not triggered;

FIG. 23 is a graph illustrating the signal count for the capacitivesensor in the exploration mode further illustrating when the switch isactivated, according to the embodiment of FIG. 21;

FIG. 24 is a graph illustrating the signal count for a capacitive sensorfurther illustrating when activations are triggered, according to theembodiment of FIG. 21;

FIG. 25 is a graph illustrating the signal count for a capacitive sensorfurther illustrating a timeout for exiting the virtual button mode andre-entering the virtual button mode, according to the embodiment of FIG.21;

FIG. 26 is a flow diagram illustrating a routine for processing thesignal channel with a virtual button mode, according to the embodimentshown in FIG. 21;

FIG. 27 is a flow diagram illustrating a virtual button method forprocessing the signal channel, according to the embodiment of FIG. 21;

FIG. 28A is a cross-sectional view of a proximity switch assembly havingproximity switches and an overlying pliable material in relation to auser's finger shown in a first position, according to anotherembodiment;

FIG. 28B is a cross-sectional view of the proximity switch assembly ofFIG. 28A further illustrating the user's finger in a second position;

FIG. 28C is a cross-sectional view of the proximity switch assembly ofFIG. 28A further illustrating depression of the finger into the pliablelayer in a third position;

FIG. 28D is a graph illustrating the signal generated by one of theproximity sensors in response to movement of the finger and depressionof the pliable cover as seen in FIGS. 28A-28C;

FIG. 29A is a cross-sectional view of a proximity switch assemblyemploying a pliable cover material having elevated regions with air gapsand a user's finger shown in a first position, according to a furtherembodiment;

FIG. 29B is a cross-sectional view of the proximity switch assembly ofFIG. 29A further illustrating the user's finger in a second position;

FIG. 29C is a cross-sectional view of the proximity switch assembly asseen in FIG. 29A further illustrating depression of the switch by auser's finger in a third position;

FIG. 29D is a graph illustrating a signal generated by one of thesensors in response to movement of the finger as shown in FIGS. 29A-29C;

FIG. 30 is a state diagram illustrating various states of the capacitiveswitch assembly having the pliable material covering and virtual buttonmode;

FIG. 31 is a flow diagram illustrating a routine for processing thesignal generated with a proximity switch having a pliable materialcovering, according to one embodiment;

FIG. 32 is a perspective cross-sectional view of a vehicle overheadconsole having a proximity switch assembly employing depressions in thesubstrate and a pliable covering, according to one embodiment;

FIG. 33 is a top view of the overhead console and switch assembly shownin FIG. 32 with the sensors and depressions shown in hidden dashedlines;

FIG. 34A is a cross-sectional view of the proximity switch assemblyshown in FIG. 32, and a user's finger shown in a first position,according to one embodiment;

FIG. 34B is a cross-sectional view of the proximity switch assembly ofFIG. 34A further illustrating the user's finger in a second position;

FIG. 34C is a cross-sectional view of the proximity switch assembly asseen in FIG. 34A further illustrating depression of the switch by auser's finger in a third position;

FIG. 34D is a graph illustrating a signal generated by one of theproximity sensors in response to movement of the finger as shown inFIGS. 34A-34C;

FIG. 35 is a perspective cross-sectional view of a vehicle overheadconsole having a proximity switch assembly employing a groove betweenadjacent sensors, according to another embodiment;

FIG. 36 is a top view of the overhead console and switch assembly shownin FIG. 35 with the sensors, depressions and grooves shown in hiddenlines;

FIG. 37A is a cross-sectional view of the proximity switch assemblyshown in FIG. 35, and a user's finger shown in a first position,according to another embodiment;

FIG. 37B is a cross-sectional view of the proximity switch assembly ofFIG. 37A further illustrating the user's finger in a second position;

FIG. 37C is a cross-sectional view of the proximity switch assembly asseen in FIG. 37A further illustrating the user's finger in a thirdposition;

FIG. 37D is a cross-sectional view of the proximity switch assembly asseen in FIG. 37A further illustrating the user's finger in a fourthposition;

FIG. 37E is a graph illustrating two signals generated by two of thesensors in response to movement of the finger as shown in FIGS. 37A-37D;and

FIG. 38 is a cross-sectional view of a proximity switch assemblyemploying a pliable cover material having a depression and an elevatedregion in the pliable material above each depression, according to afurther embodiment.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

As required, detailed embodiments of the present invention are disclosedherein; however, it is to be understood that the disclosed embodimentsare merely exemplary of the invention that may be embodied in variousand alternative forms. The figures are not necessarily to a detaileddesign; some schematics may be exaggerated or minimized to show functionoverview. Therefore, specific structural and functional detailsdisclosed herein are not to be interpreted as limiting, but merely as arepresentative basis for teaching one skilled in the art to variouslyemploy the present invention.

Referring to FIGS. 1 and 2, the interior of an automotive vehicle 10 isgenerally illustrated having a passenger compartment and a switchassembly 20 employing a plurality of proximity switches 22 having switchactivation monitoring and determination, according to one embodiment.The vehicle 10 generally includes an overhead console 12 assembled tothe headliner on the underside of the roof or ceiling at the top of thevehicle passenger compartment, generally above the front passengerseating area. The switch assembly 20 has a plurality of proximityswitches 22 arranged close to one another in the overhead console 12,according to one embodiment. The various proximity switches 22 maycontrol any of a number of vehicle devices and functions, such ascontrolling movement of a sunroof or moonroof 16, controlling movementof a moonroof shade 18, controlling activation of one or more lightingdevices such as interior map/reading and dome lights 30, and variousother devices and functions. However, it should be appreciated that theproximity switches 22 may be located elsewhere on the vehicle 10, suchas in the dash panel, on other consoles such as a center console,integrated into a touch screen display 14 for a radio or infotainmentsystem such as a navigation and/or audio display, or located elsewhereonboard the vehicle 10 according to various vehicle applications.

The proximity switches 22 are shown and described herein as capacitiveswitches, according to one embodiment. Each proximity switch 22 includesat least one proximity sensor that provides a sense activation field tosense contact or close proximity (e.g., within one millimeter) of a userin relation to the one or more proximity sensors, such as a swipingmotion by a user's finger. Thus, the sense activation field of eachproximity switch 22 is a capacitive field in the exemplary embodimentand the user's finger has electrical conductivity and dielectricproperties that cause a change or disturbance in the sense activationfield as should be evident to those skilled in the art. However, itshould also be appreciated by those skilled in the art that additionalor alternative types of proximity sensors can be used, such as, but notlimited to, inductive sensors, optical sensors, temperatures sensors,resistive sensors, the like, or a combination thereof. Exemplaryproximity sensors are described in the Apr. 9, 2009, ATMEL® TouchSensors Design Guide, 10620 D-AT42-04/09, the entire reference herebybeing incorporated herein by reference.

The proximity switches 22 shown in FIGS. 1 and 2 each provide control ofa vehicle component or device or provide a designated control function.One or more of the proximity switches 22 may be dedicated to controllingmovement of a sunroof or moonroof 16 so as to cause the moonroof 16 tomove in an open or closed direction, tilt the moonroof, or stop movementof the moonroof based upon a control algorithm. One or more otherproximity switches 22 may be dedicated to controlling movement of amoonroof shade 18 between open and closed positions. Each of themoonroof 16 and shade 18 may be actuated by an electric motor inresponse to actuation of the corresponding proximity switch 22. Otherproximity switches 22 may be dedicated to controlling other devices,such as turning an interior map/reading light 30 on, turning an interiormap/reading light 30 off, turning a dome lamp on or off, unlocking atrunk, opening a rear hatch, or defeating a door light switch.Additional controls via the proximity switches 22 may include actuatingdoor power windows up and down. Various other vehicle controls may becontrolled by way of the proximity switches 22 described herein.

Referring to FIG. 3, a portion of the proximity switch assembly 20 isillustrated having an array of three serially arranged proximityswitches 22 in close relation to one another in relation to a user'sfinger 34 during use of the switch assembly 20. Each proximity switch 22includes one or more proximity sensors 24 for generating a senseactivation field. According to one embodiment, each of the proximitysensors 24 may be formed by printing conductive ink onto the top surfaceof the polymeric overhead console 12. One example of a printed inkproximity sensor 24 is shown in FIG. 4 generally having a driveelectrode 26 and a receive electrode 28 each having interdigitatedfingers for generating a capacitive field 32. It should be appreciatedthat each of the proximity sensors 24 may be otherwise formed such as byassembling a preformed conductive circuit trace onto a substrateaccording to other embodiments. The drive electrode 26 receives squarewave drive pulses applied at voltage V_(I). The receive electrode 28 hasan output for generating an output voltage V_(O). It should beappreciated that the electrodes 26 and 28 may be arranged in variousother configurations for generating the capacitive field as theactivation field 32.

In the embodiment shown and described herein, the drive electrode 26 ofeach proximity sensor 24 is applied with voltage input V_(I) as squarewave pulses having a charge pulse cycle sufficient to charge the receiveelectrode 28 to a desired voltage. The receive electrode 28 therebyserve as a measurement electrode. In the embodiment shown, adjacentsense activation fields 32 generated by adjacent proximity switches 22overlap slightly, however, overlap may not exist according to otherembodiments. When a user or operator, such as the user's finger 34,enters an activation field 32, the proximity switch assembly 20 detectsthe disturbance caused by the finger 34 to the activation field 32 anddetermines whether the disturbance is sufficient to activate thecorresponding proximity switch 22. The disturbance of the activationfield 32 is detected by processing the charge pulse signal associatedwith the corresponding signal channel. When the user's finger 34contacts two activation fields 32, the proximity switch assembly 20detects the disturbance of both contacted activation fields 32 viaseparate signal channels. Each proximity switch 22 has its own dedicatedsignal channel generating charge pulse counts which is processed asdiscussed herein.

Referring to FIG. 5, the proximity switch assembly 20 is illustratedaccording to one embodiment. A plurality of proximity sensors 24 areshown providing inputs to a controller 40, such as a microcontroller.The controller 40 may include control circuitry, such as amicroprocessor 42 and memory 48. The control circuitry may include sensecontrol circuitry processing the activation field of each sensor 22 tosense user activation of the corresponding switch by comparing theactivation field signal to one or more thresholds pursuant to one ormore control routines. It should be appreciated that other analog and/ordigital control circuitry may be employed to process each activationfield, determine user activation, and initiate an action. The controller40 may employ a QMatrix acquisition method available by ATMEL®,according to one embodiment. The ATMEL acquisition method employs aWINDOWS® host C/C++ compiler and debugger WinAVR to simplify developmentand testing the utility Hawkeye that allows monitoring in real-time theinternal state of critical variables in the software as well ascollecting logs of data for post-processing.

The controller 40 provides an output signal to one or more devices thatare configured to perform dedicated actions responsive to correctactivation of a proximity switch. For example, the one or more devicesmay include a moonroof 16 having a motor to move the moonroof panelbetween open and closed and tilt positions, a moonroof shade 18 thatmoves between open and closed positions, and lighting devices 30 thatmay be turned on and off. Other devices may be controlled such as aradio for performing on and off functions, volume control, scanning, andother types of devices for performing other dedicated functions. One ofthe proximity switches 22 may be dedicated to actuating the moonroofclosed, another proximity switch 22 may be dedicated to actuating themoonroof open, and a further switch 22 may be dedicated to actuating themoonroof to a tilt position, all of which would cause a motor to movethe moonroof to a desired position. The moonroof shade 18 may be openedin response to one proximity switch 22 and may be closed responsive toanother proximity switch 22.

The controller 40 is further shown having an analog to digital (A/D)comparator 44 coupled to the microprocessor 42. The A/D comparator 44receives the voltage output V_(O) from each of the proximity switches22, converts the analog signal to a digital signal, and provides thedigital signal to the microprocessor 42. Additionally, controller 40includes a pulse counter 46 coupled to the microprocessor 42. The pulsecounter 46 counts the charge signal pulses that are applied to eachdrive electrode of each proximity sensor, performs a count of the pulsesneeded to charge the capacitor until the voltage output V_(O) reaches apredetermined voltage, and provides the count to the microprocessor 42.The pulse count is indicative of the change in capacitance of thecorresponding capacitive sensor. The controller 40 is further showncommunicating with a pulse width modulated drive buffer 15. Thecontroller 40 provides a pulse width modulated signal to the pulse widthmodulated drive buffer 15 to generate a square wave pulse train V_(I)which is applied to each drive electrode of each proximity sensor/switch22. The controller 40 processes a control routine 100 stored in memoryto monitor and make a determination as to activation of one of theproximity switches.

In FIGS. 6-13, the change in sensor charge pulse counts shown as ASensor Count for a plurality of signal channels associated with aplurality of proximity switches 22, such as the three switches 22 shownin FIG. 3, is illustrated according to various examples. The change insensor charge pulse count is the difference between an initializedreferenced count value without any finger or other object present in theactivation field and the corresponding sensor reading. In theseexamples, the user's finger enters the activation fields 32 associatedwith each of three proximity switches 22, generally one sense activationfield at a time with overlap between adjacent activation fields 32 asthe user's finger moves across the array of switches. Channel 1 is thechange (Δ) in sensor charge pulse count associated with a firstcapacitive sensor 24, channel 2 is the change in sensor charge pulsecount associated with the adjacent second capacitive sensor 24, andchannel 3 is the change in sensor charge pulse count associated with thethird capacitive sensor 24 adjacent to the second capacitive sensor. Inthe disclosed embodiment, the proximity sensors 24 are capacitivesensors. When a user's finger is in contact with or close proximity of asensor 24, the finger alters the capacitance measured at thecorresponding sensor 24. The capacitance is in parallel to the untouchedsensor pad parasitic capacitance, and as such, measures as an offset.The user or operator induced capacitance is proportional to the user'sfinger or other body part dielectric constant, the surface exposed tothe capacitive pad, and is inversely proportional to the distance of theuser's limb to the switch button. According to one embodiment, eachsensor is excited with a train of voltage pulses via pulse widthmodulation (PWM) electronics until the sensor is charged up to a setvoltage potential. Such an acquisition method charges the receiveelectrode 28 to a known voltage potential. The cycle is repeated untilthe voltage across the measurement capacitor reaches a predeterminedvoltage. Placing a user's finger on the touch surface of the switch 24introduces external capacitance that increases the amount of chargetransferred each cycle, thereby reducing the total number of cyclesrequired for the measurement capacitance to reach the predeterminedvoltage. The user's finger causes the change in sensor charge pulsecount to increase since this value is based on the initialized referencecount minus the sensor reading.

The proximity switch assembly 20 is able to recognize the user's handmotion when the hand, particularly a finger, is in close proximity tothe proximity switches 22, to discriminate whether the intent of theuser is to activate a switch 22, explore for a specific switch buttonwhile focusing on higher priority tasks, such as driving, or is theresult of a task such as adjusting the rearview mirror that has nothingto do with actuation of a proximity switch 22. The proximity switchassembly 20 may operate in an exploration or hunting mode which enablesthe user to explore the keypads or buttons by passing or sliding afinger in close proximity to the switches without triggering anactivation of a switch until the user's intent is determined. Theproximity switch assembly 20 monitors amplitude of a signal generated inresponse to the activation field, determines a differential change inthe generated signal, and generates an activation output when thedifferential signal exceeds a threshold. As a result, exploration of theproximity switch assembly 20 is allowed, such that users are free toexplore the switch interface pad with their fingers withoutinadvertently triggering an event, the interface response time is fast,activation happens when the finger contacts a surface panel, andinadvertent activation of the switch is prevented or reduced.

Referring to FIG. 6, as the user's finger 34 approaches a switch 22associated with signal channel 1, the finger 34 enters the activationfield 32 associated with the sensor 24 which causes disruption to thecapacitance, thereby resulting in a sensor count increase as shown bysignal 50A having a typical activation motion profile. An entry rampslope method may be used to determine whether the operator intends topress a button or explore the interface based on the slope of the entryramp in signal 50A of the channel 1 signal rising from point 52 wheresignal 50A crosses the level active (LVL_ACTIVE) count up to point 54where signal 50A crosses the level threshold (LVL_THRESHOLD) count,according to one embodiment. The slope of the entry ramp is thedifferential change in the generated signal between points 52 and 54which occurred during the time period between times t_(th) and t_(ac).Because the numerator level threshold—level active generally changesonly as the presence of gloves is detected, but is otherwise a constant,the slope can be calculated as just the time expired to cross from levelactive to level threshold referred to as t_(active2threshold) which isthe difference between time t_(th) and t_(ac). A direct push on a switchpad typically may occur in a time period referred to t_(directpush) inthe range of about 40 to 60 milliseconds. If the timet_(active2threshold) is less than or equal to the direct push timet_(directpush), then activation of the switch is determined to occur.Otherwise, the switch is determined to be in an exploration mode.

According to another embodiment, the slope of the entry ramp may becomputed as the difference in time from the time t_(ac) at point 52 totime t_(pk) to reach the peak count value at point 56, referred to astime t_(active2peak). The time t_(active2peak). may be compared to adirect push peak, referred to as t_(direct) _(—) _(push) _(—) _(pk)which may have a value of 100 milliseconds according to one embodiment.If time t_(active2peak) is less than or equal to the t_(direct) _(—)_(push) _(—) _(pk) activation of the switch is determined to occur.Otherwise, the switch assembly operates in an exploration mode.

In the example shown in FIG. 6, the channel 1 signal is shown increasingas the capacitance disturbance increases rising quickly from point 52 topeak value at point 56. The proximity switch assembly 20 determines theslope of the entry ramp as either time period t_(active2threshold) ort_(active2peak) for the signal to increase from the first thresholdpoint 52 to either the second threshold at point 54 or the peakthreshold at point 56. The slope or differential change in the generatedsignal is then used for comparison with a representative direct pushthreshold t_(direct) _(—) _(push) or t_(direct) _(—) _(push) _(—) _(pk)to determine activation of the proximity switch. Specifically, when timet_(active2peak) is less than the t_(direct) _(—) _(push) ort_(active2threshold) is less than t_(direct) _(—) _(push), activation ofthe switch is determined. Otherwise, the switch assembly remains in theexploration mode.

Referring to FIG. 7, one example of a sliding/exploration motion acrosstwo switches is illustrated as the finger passes or slides through theactivation field of two adjacent proximity sensors shown as signalchannel 1 labeled 50A and signal channel 2 labeled 50B. As the user'sfinger approaches a first switch, the finger enters the activation fieldassociated with the first switch sensor causing the change in sensorcount on signal 50A to increase at a slower rate such that a lesseneddifferential change in the generated signal is determined. In thisexample, the profile of signal channel 1 experiences a change in timet_(active2peak) that is not less than or equal to t_(direct) _(—)_(push), thereby resulting in entering the hunting or exploration mode.Because the t_(active2threshold) is indicative of a slow differentialchange in the generated signal, no activation of the switch button isinitiated, according to one embodiment. According to another embodiment,because the time t_(active2peak) is not less than or equal to t_(direct)_(—) _(push) _(—) _(pk), indicative of a slow differential change in agenerated signal, no activation is initiated, according to anotherembodiment. The second signal channel labeled 50B is shown as becomingthe maximum signal at transition point 58 and has a rising change in Δsensor count with a differential change in the signal similar to that ofsignal 50A. As a result, the first and second channels 50A and 50Breflect a sliding motion of the finger across two capacitive sensors inthe exploration mode resulting in no activation of either switch. Usingthe time period t_(active2threshold) or t_(active2peak), a decision canbe made to activate or not a proximity switch as its capacitance levelreaches the signal peak.

For a slow direct push motion such as shown in FIG. 8, additionalprocessing may be employed to make sure that no activation is intended.As seen in FIG. 8, the signal channel 1 identified as signal 50A isshown more slowly rising during either time period t_(active2threshold)or t_(active2peak) which would result in the entering of the explorationmode. When such a sliding/exploration condition is detected, with thetime t_(active2threshold) greater than t_(direct) _(—) _(push) if thechannel failing the condition was the first signal channel entering theexploration mode and it is still the maximum channel (channel with thehighest intensity) as its capacitance drops below LVL_KEYUP_Threshold atpoint 60, then activation of the switch is initiated.

Referring to FIG. 9, a fast motion of a user's finger across theproximity switch assembly is illustrated with no activation of theswitches. In this example, the relatively large differential change inthe generated signal for channels 1 and 2 are detected, for bothchannels 1 and 2 shown by lines 50A and 50B, respectively. The switchassembly employs a delayed time period to delay activation of a decisionuntil the transition point 58 at which the second signal channel 50Brises above the first signal channel 50A. The time delay could be setequal to time threshold t_(direct) _(—) _(push) _(—) _(pk) according toone embodiment. Thus, by employing a delay time period beforedetermining activation of a switch, the very fast exploration of theproximity keypads prevents an unintended activation of a switch. Theintroduction of the time delay in the response may make the interfaceless responsive and may work better when the operator's finger motion issubstantially uniform.

If a previous threshold event that did not result in activation wasrecently detected, the exploration mode may be entered automatically,according to one embodiment. As a result, once an inadvertent actuationis detected and rejected, more caution may be applied for a period oftime in the exploration mode.

Another way to allow an operator to enter the exploration mode is to useone or more properly marked and/or textured areas or pads on the switchpanel surface associated with the dedicated proximity switches with thefunction of signaling the proximity switch assembly of the intent of theoperator to blindly explore. The one or more exploration engagement padsmay be located in an easy to reach location not likely to generateactivity with other signal channels. According to another embodiment, anunmarked, larger exploration engagement pad may be employed surroundingthe entire switch interface. Such an exploration pad would likely beencountered first as the operator's hand slides across the trim in theoverhead console looking for a landmark from which to start blindexploration of the proximity switch assembly.

Once the proximity sensor assembly determines whether an increase in thechange in sensor count is a switch activation or the result of anexploration motion, the assembly proceeds to determine whether and howthe exploration motion should terminate or not in an activation ofproximity switch. According to one embodiment, the proximity switchassembly looks for a stable press on a switch button for at least apredetermined amount of time. In one specific embodiment, thepredetermined amount of time is equal to or greater than 50milliseconds, and more preferably about 80 milliseconds. Examples of theswitch assembly operation employing a stable time methodology isillustrated in FIGS. 10-13.

Referring to FIG. 10, the exploration of three proximity switchescorresponding to signal channels 1-3 labeled as signals 50A-50C,respectively, is illustrated while a finger slides across first andsecond switches in the exploration mode and then activates the thirdswitch associated with signal channel 3. As the finger explores thefirst and second switches associated with channels 1 and 2, noactivation is determined due to no stable signal on lines 50A and 50B.The signal on line 50A for channel 1 begins as the maximum signal valueuntil channel 2 on line 50B becomes the maximum value and finallychannel 3 becomes a maximum value. Signal channel 3 is shown having astable change in sensor count near the peak value for a sufficient timeperiod t_(stable) such as 80 milliseconds which is sufficient toinitiate activation of the corresponding proximity switch. When thelevel threshold trigger condition has been met and a peak has beenreached, the stable level method activates the switch after the level onthe switch is bound in a tight range for at least the time periodt_(stable). This allows the operator to explore the various proximityswitches and to activate a desired switch once it is found bymaintaining position of the user's finger in proximity to the switch fora stable period of time t_(stable).

Referring to FIG. 11, another embodiment of the stable level method isillustrated in which the third signal channel on line 50C has a changein sensor count that has a stable condition on the descent of thesignal. In this example, the change in sensor count for the thirdchannel exceeds the level threshold and has a stable press detected forthe time period t_(stable) such that activation of the third switch isdetermined.

According to another embodiment, the proximity switch assembly mayemploy a virtual button method which looks for an initial peak value ofchange in sensor count while in the exploration mode followed by anadditional sustained increase in the change in sensor count to make adetermination to activate the switch as shown in FIGS. 12 and 13. InFIG. 12, the third signal channel on line 50C rises up to an initialpeak value and then further increases by a change in sensor countC_(vb). This is equivalent to a user's finger gently brushing thesurface of the switch assembly as it slides across the switch assembly,reaching the desired button, and then pressing down on the virtualmechanical switch such that the user's finger presses on the switchcontact surface and increases the amount of volume of the finger closerto the switch. The increase in capacitance is caused by the increasedsurface of the fingertip as it is compressed on the pad surface. Theincreased capacitance may occur immediately following detection of apeak value shown in FIG. 12 or may occur following a decline in thechange in sensor count as shown in FIG. 13. The proximity switchassembly detects an initial peak value followed by a further increasedchange in sensor count indicated by capacitance C_(vb) at a stable levelor a stable time period t_(stable). A stable level of detectiongenerally means no change in sensor count value absent noise or a smallchange in sensor count value absent noise which can be predeterminedduring calibration.

It should be appreciated that a shorter time period t_(stable) mayresult in accidental activations, especially following a reversal in thedirection of the finger motion and that a longer time period t_(stable)may result in a less responsive interface.

It should also be appreciated that both the stable value method and thevirtual button method can be active at the same time. In doing so, thestable time t_(stable) can be relaxed to be longer, such as one second,since the operator can always trigger the button using the virtualbutton method without waiting for the stable press time-out.

The proximity switch assembly may further employ robust noise rejectionto prevent annoying inadvertent actuations. For example, with anoverhead console, accidental opening and closing of the moonroof shouldbe avoided. Too much noise rejection may end up rejecting intendedactivations, which should be avoided. One approach to rejecting noise isto look at whether multiple adjacent channels are reporting simultaneoustriggering events and, if so, selecting the signal channel with thehighest signal and activating it, thereby ignoring all other signalchannels until the release of the select signal channel.

The proximity switch assembly 20 may include a signature noise rejectionmethod based on two parameters, namely a signature parameter that is theratio between the channel between the highest intensity (max_channel)and the overall cumulative level (sum_channel), and the dac parameterwhich is the number of channels that are at least a certain ratio of themax_channel. In one embodiment, the dac α_(dac)=0.5. The signatureparameter may be defined by the following equation:

${signature} = {\frac{max\_ channel}{sum\_ channel} = {\frac{\max_{{i = 0},n}{channel}_{i}}{\sum\limits_{{i = 0},n}{channel}_{i}}.}}$

The dac parameter may be defined by the following equation:

dac=∀channels_(i)>α_(dac)max_channel.

Depending on dac, for a recognized activation not to be rejected, thechannel generally must be clean, i.e., the signature must be higher thana predefined threshold. In one embodiment, α_(dac=1)=0.4, andα_(dac=2)=0.67. If the dac is greater than 2, the activation is rejectedaccording to one embodiment.

When a decision to activate a switch or not is made on the descendingphase of the profile, then instead of max_channel and sum_channel theirpeak values peak_max_channel and peak_sum_channel may be used tocalculate the signature. The signature may have the following equation:

${signature} = {\frac{{peak\_ max}{\_ channel}}{{peak\_ sum}{\_ channel}} = {\frac{\max ( {{max\_ channel}(t)} )}{\max ( {{sum\_ channel}(t)} )}.}}$

A noise rejection triggers hunting mode may be employed. When a detectedactivation is rejected because of a dirty signature, the hunting orexploration mode should be automatically engaged. Thus, when blindlyexploring, a user may reach with all fingers extended looking toestablish a reference frame from which to start hunting. This maytrigger multiple channels at the same time, thereby resulting in a poorsignature.

Referring to FIG. 14, a state diagram is shown for the proximity switchassembly 20 in a state machine implementation, according to oneembodiment. The state machine implementation is shown having five statesincluding SW_NONE state 70, SW_ACTIVE state 72, SW_THRESHOLD state 74,SW_HUNTING state 76 and SWITCH_ACTIVATED state 78. The SW_NONE state 70is the state in which there is no sensor activity detected. TheSW_ACTIVE state is the state in which some activity is detected by thesensor, but not enough to trigger activation of the switch at that pointin time. The SW_THRESHOLD state is the state in which activity asdetermined by the sensor is high enough to warrant activation,hunting/exploration, or casual motion of the switch assembly. TheSW_HUNTING state 76 is entered when the activity pattern as determinedby the switch assembly is compatible with the exploration/huntinginteraction. The SWITCH_ACTIVATED state 78 is the state in whichactivation of a switch has been identified. In the SWITCH_ACTIVATEDstate 78, the switch button will remain active and no other selectionwill be possible until the corresponding switch is released.

The state of the proximity switch assembly 20 changes depending upon thedetection and processing of the sensed signals. When in the SW_NONEstate 70, the system 20 may advance to the SW_ACTIVE state 72 when someactivity is detected by one or more sensors. If enough activity towarrant either activation, hunting or casual motion is detected, thesystem 20 may proceed directly to the SW_THRESHOLD state 74. When in theSW_THRESHOLD state 74, the system 20 may proceed to the SW_HUNTING state76 when a pattern indicative of exploration is detected or may proceeddirectly to switch activated state 78. When a switch activation is inthe SW_HUNTING state, an activation of the switch may be detected tochange to the SWITCH_ACTIVATED state 78. If the signal is rejected andinadvertent action is detected, the system 20 may return to the SW_NONEstate 70.

Referring to FIG. 15, the main method 100 of monitoring and determiningwhen to generate an activation output with the proximity switcharrangement is shown, according to one embodiment. Method 100 begins atstep 102 and proceeds to step 104 to perform an initial calibrationwhich may be performed once. The calibrated signal channel values arecomputed from raw channel data and calibrated reference values bysubtracting the reference value from the raw data in step 106. Next, atstep 108, from all signal channel sensor readings, the highest countvalue referenced as max_channel and the sum of all channel sensorreadings referred to as sum_channel are calculated. In addition, thenumber of active channels is determined. At step 110, method 100calculates the recent range of the max_channel and the sum_channel todetermine later whether motion is in progress or not.

Following step 110, method 100 proceeds to decision step 112 todetermine if any of the switches are active. If no switch is active,method 100 proceeds to step 114 to perform an online real-timecalibration. Otherwise, method 116 processes the switch release at step116. Accordingly, if a switch was already active, then method 100proceeds to a module where it waits and locks all activity until itsrelease.

Following the real-time calibration, method 100 proceeds to decisionstep 118 to determine if there is any channel lockout indicative ofrecent activation and, if so, proceeds to step 120 to decrease thechannel lockout timer. If there are no channel lockouts detected, method100 proceeds to decision step 122 to look for a new max_channel. If thecurrent max_channel has changed such that there is a new max_channel,method 100 proceeds to step 124 to reset the max_channel, sum theranges, and set the threshold levels. Thus, if a new max_channel isidentified, the method resets the recent signal ranges, and updates, ifneeded, the hunting/exploration parameters. If the switch_status is lessthan SW_ACTIVE, then the hunting/exploration flag is set equal to trueand the switch status is set equal to SW_NONE. If the currentmax_channel has not changed, method 100 proceeds to step 126 to processthe max_channel naked (no glove) finger status. This may includeprocessing the logic between the various states as shown in the statediagram of FIG. 14.

Following step 126, method 100 proceeds to decision step 128 todetermine if any switch is active. If no switch activation is detected,method 100 proceeds to step 130 to detect a possible glove presence onthe user's hand. The presence of a glove may be detected based on areduced change in capacitance count value. Method 100 then proceeds tostep 132 to update the past history of the max_channel and sum_channel.The index of the active switch, if any, is then output to the softwarehardware module at step 134 before ending at step 136.

When a switch is active, a process switch release routine is activatedwhich is shown in FIG. 16. The process switch release routine 116 beginsat step 140 and proceeds to decision step 142 to determine if the activechannel is less than LVL_RELEASE and, if so, ends at step 152. If theactive channel is less than the LVL_RELEASE then routine 116 proceeds todecision step 144 to determine if the LVL_DELTA_THRESHOLD is greaterthan 0 and, if not, proceeds to step 146 to raise the threshold level ifthe signal is stronger. This may be achieved by decreasingLVL_DELTA_THRESHOLD. Step 146 also sets the threshold, release andactive levels. Routine 116 then proceeds to step 148 to reset thechannel max and sum history timer for long stable signalhunting/exploration parameters. The switch status is set equal toSW_NONE at step 150 before ending at step 152. To exit the processswitch release module, the signal on the active channel has to dropbelow LVL_RELEASE, which is an adaptive threshold that will change asglove interaction is detected. As the switch button is released, allinternal parameters are reset and a lockout timer is started to preventfurther activations before a certain waiting time has elapsed, such as100 milliseconds. Additionally, the threshold levels are adapted infunction of the presence of gloves or not.

Referring to FIG. 17, a routine 200 for determining the status changefrom SW_NONE state to SW_ACTIVE state is illustrated, according to oneembodiment. Routine 200 begins at step 202 to process the SW_NONE state,and then proceeds to decision step 204 to determine if the max_channelis greater than LVL_ACTIVE. If the max_channel is greater thanLVL_ACTIVE, then the proximity switch assembly changes state fromSW_NONE state to SW_ACTIVE state and ends at step 210. If themax_channel is not greater than LVL_ACTIVE, the routine 200 checks forwhether to reset the hunting flag at step 208 prior to ending at step210. Thus, the status changes from SW_NONE state to SW_ACTIVE state whenthe max_channel triggers above LVL_ACTIVE. If the channels stays belowthis level, after a certain waiting period, the hunting flag, if set,gets reset to no hunting, which is one way of departing from the huntingmode.

Referring to FIG. 18, a method 220 for processing the state of theSW_ACTIVE state changing to either SW_THRESHOLD state or SW_NONE stateis illustrated, according to one embodiment. Method 220 begins at step222 and proceeds to decision step 224. If max_channel is not greaterthan LVL_THRESHOLD, then method 220 proceeds to step 226 to determine ifthe max_channel is less than LVL_ACTIVE and, if so, proceeds to step 228to change the switch status to SW_NONE. Accordingly, the status of thestate machine moves from the SW_ACTIVE state to SW_NONE state when themax_channel signal drops below LVL_ACTIVE. A delta value may also besubtracted from LVL_ACTIVE to introduce some hysteresis. If themax_channel is greater than the LVL_THRESHOLD, then routine 220 proceedsto decision step 230 to determine if a recent threshold event or a glovehas been detected and, if so, sets the hunting on flag equal to true atstep 232. At step 234, method 220 switches the status to SW_THRESHOLDstate before ending at step 236. Thus, if the max_channel triggers abovethe LVL_THRESHOLD, the status changes to SW_THRESHOLD state. If glovesare detected or a previous threshold event that did not result inactivation was recently detected, then the hunting/exploration mode maybe entered automatically.

Referring to FIG. 19, a method 240 of determining activation of a switchfrom the SW_THRESHOLD state is illustrated, according to one embodiment.Method 240 begins at step 242 to process the SW_THRESHOLD state andproceeds to decision block 244 to determine if the signal is stable orif the signal channel is at a peak and, if not, ends at step 256. Ifeither the signal is stable or the signal channel is at a peak, thenmethod 240 proceeds to decision step 246 to determine if the hunting orexploration mode is active and, if so, skips to step 250. If the huntingor exploration mode is not active, method 240 proceeds to decision step248 to determine if the signal channel is clean and fast active isgreater than a threshold and, if so, sets the switch active equal to themaximum channel at step 250. Method 240 proceeds to decision block 252to determine if there is a switch active and, if so, ends at step 256.If there is no switch active, method 240 proceeds to step 254 toinitialize the hunting variables SWITCH_STATUS set equal toSWITCH_HUNTING and PEAK_MAX_BASE equal to MAX_CHANNELS, prior to endingat step 256.

In the SW_THRESHOLD state, no decision is taken until a peak inMAX_CHANNEL is detected. Detection of the peak value is conditioned oneither a reversal in the direction of the signal, or both theMAX_CHANNEL and SUM_CHANNEL remaining stable (bound in a range) for atleast a certain interval, such as 60 milliseconds. Once the peak isdetected, the hunting flag is checked. If the hunting mode is off, theentry ramp slope method is applied. If the SW_ACTIVE to SW_THRESHOLD wasa less than a threshold such as 16 milliseconds, and the signature ofnoise rejection method indicates it as a valid triggering event, thenthe state is changed to SWITCH_ACTIVE and the process is transferred tothe PROCESS_SWITCH_RELEASE module, otherwise the hunting flag is setequal to true. If the delayed activation method is employed instead ofimmediately activating the switch, the state is changed toSW_DELAYED_ACTIVATION where a delay is enforced at the end of which, ifthe current MAX_CHANNEL index has not changed, the button is activated.

Referring to FIG. 20, a virtual button method implementing theSW_HUNTING state is illustrated, according to one embodiment. The method260 begins at step 262 to process the SW_HUNTING state and proceeds todecision step 264 to determine if the MAX_CHANNEL has dropped below theLVL_KEYUP_THRESHOLD_and, if so, sets the MAX_PEAK_BASE equal to MIN(MAX_PEAK_BASE, MAX_CHANNEL) at step 272. If the MAX_CHANNEL has droppedbelow the LVL_KEYUP_THRESHOLD, then method 260 proceeds to step 266 toemploy the first channel triggering hunting method to check whether theevent should trigger the button activation. This is determined bydetermining if the first and only channel is traversed and the signal isclean. If so, method 260 sets the switch active equal to the maximumchannel at step 270 before ending at step 282. If the first and onlychannel is not traversed or if the signal is not clean, method 260proceeds to step 268 to give up and determine an inadvertent actuationand to set the SWITCH_STATUS equal to SW_NONE state before ending atstep 282.

Following step 272, method 260 proceeds to decision step 274 todetermine if the channel clicked. This can be determined by whetherMAX_CHANNEL is greater than MAX_PEAK_BASE plus delta. If the channel hasclicked, method 260 proceeds to decision step 276 to determine if thesignal is stable and clean and, if so, sets the switch active state tothe maximum channel at step 280 before ending at step 282. If thechannel has not clicked, method 260 proceeds to decision step 278 to seeif the signal is long, stable and clean, and if so, proceeds to step 280to set the switch active equal to the maximum channel before ending atstep 282.

The proximity switch assembly 20 may include a virtual button mode,according to another embodiment. Referring to FIGS. 21-27, the proximityswitch assembly having a virtual button mode and a method of activatingthe proximity switch with the virtual button mode is shown therein,according to this embodiment. The proximity switch assembly may includeone or more proximity switches each providing a sense activation fieldand control circuitry for controlling the activation field of eachproximity switch to sense activation. The control circuitry monitorssignals indicative of the activation fields, determines a first stableamplitude of the signal for a time period, determines a subsequentsecond stable amplitude of the signal for the time period, and generatesan activation output when the second stable signal exceeds the firststable signal by a known amount. The method may be employed by theproximity switch assembly and includes the steps of generating anactivation field associated with each of one or more of a plurality ofproximity sensors, and monitoring a signal indicative of each associatedactivation field. The method also includes the steps of determining afirst amplitude when the signal is stable for a minimum time period, anddetermining a second amplitude when the signal is stable for the minimumtime period. The method further includes the step of generating anactivation output when the second amplitude exceeds the first amplitudeby a known amount. As a result, a virtual button mode is provided forthe proximity switch that prevents or reduces unintended or falseactivations which may be caused by a finger exploring a plurality ofproximity switch buttons and changing directions or by a finger coveredby a glove.

In FIG. 21, the exploration and activation of a proximity switch isshown for one of the signal channels labeled as signal 50 as a user'sfinger slides across the corresponding switch, enters an explorationmode, and proceeds to activate the switch in the virtual button mode. Itshould be appreciated that the user's finger may explore a plurality ofcapacitive switches as illustrated in FIGS. 10-12 in which signalsassociated with each of the corresponding signal channels are generatedas the finger passes through the activation field of each channel. Aplurality of signal channels may be processed at the same time and themaximum signal channel may be processed to determine activation of thecorresponding proximity switch. In the examples provided in the signaldiagrams of FIGS. 21-25, a single signal channel associated with oneswitch is shown, however, a plurality of signal channels could beprocessed. The signal 50 associated with one of the signal channels isshown in FIG. 21 rising up to a threshold active level 320 at point 300at which point the signal enters the exploration mode. The signal 50thereafter continues to rise and reaches a first amplitude at whichpoint the signal is stable for a minimum time period, shown as Tstablewhich is shown at point 302. At point 302, the signal 50 enters thevirtual button mode and establishes a first base value Cbase which isthe delta signal count at point 302. At this point, the virtual buttonmode establishes an incremental activation threshold as a function ofthe base value Cbase multiplied by a constant K_(vb). The activationthreshold for determining an activation may be represented by:(1+K_(vb))×Cbase, wherein K_(vb) is a constant greater than zero. Thevirtual button mode continues to monitor the signal 50 to determine whenit reaches a second stable amplitude for the minimum time period Tstablewhich occurs at point 304. At this point 304, the virtual button modecompares the second stable amplitude to the first stable amplitude anddetermines if the second amplitude exceeds the first amplitude by theknown amount of K_(vb)×Cbase. If the second amplitude exceeds the firstamplitude by the known amount, an activation output for the proximityswitch is then generated.

According to this embodiment, a stable signal amplitude must bemaintained by the signal channel for at least a minimum time periodTstable prior to entering the virtual button mode or determiningactivation of the switch. The sensor value as it enters the virtualbutton mode is recorded as Cbase. The method monitors for when asubsequent stable signal amplitude is achieved again prior to a time-outperiod. If a stable signal amplitude is achieved again prior to thetime-out period expiring with a delta count value greater than a desiredpercentage, such as 12.5 percent of the prior recorded Cbase, thenactivation is triggered. According to one embodiment, a percentage deltasignal count increase of at least 10 percent is provided byK_(vb)×Cbase.

The multiplier K_(vb) is a factor of at least 0.1 or at least 10 percentof the Cbase value, according to one embodiment. According to anotherembodiment, the multiplier K_(vb) is set at about 0.125 which equivalentto 12.5 percent. The stable time period Tstable may be set to a time ofat least 50 milliseconds, according to one embodiment. According toanother embodiment, the stable time period Tstable may be set in therange of 50 to 100 milliseconds. The stable amplitude may be determinedby the signal amplitude being substantially stable in a range withintwice the size of estimated noise on the signal according to oneembodiment, or within 2.5 to 5.0 percent of the signal level, accordingto another embodiment or a combination of twice the estimated noise ofthe signal added to 2.5 to 5.0 percent of the signal level, according toa further embodiment.

Referring to FIG. 22, a signal 50 for a signal channel associated with aproximity switch is illustrated entering the exploration mode at point300 and proceeding to a reach a stable first amplitude when the stablesignal amplitude exists for a minimum time period Tstable at point 302in which the virtual button mode is entered. At this point, the Cbasevalue is determined. Thereafter, the signal 50 is shown dropping andagain rising to a second amplitude when the signal is stable for theminimum time period Tstable at point 306. However, in this situation,the second amplitude at point 306 does not exceed the base value Cbaseof the signal at point 302 by the known amount of K_(vb)×Cbase, and as aresult does not generate an activation output for the switch.

Referring to FIG. 23, a signal 50 associated with a signal channel isillustrated entering the exploration mode at point 300 and proceeding toreach a first amplitude for a stable time period Tstable at point 302 inwhich the virtual button mode is entered and Cbase is determined.Thereafter, the signal 50 continues to rise to a second amplitude thatis stable for the minimum time period Tstable at point 308. However, atpoint 308, the second amplitude does not exceed the base value Cbase ofthe signal established at the first amplitude at point 302 by the knownamount of K_(vb)×Cbase, so the proximity switch assembly does nottrigger a switch output. However, a new updated base value is generatedfor Cbase at point 308 and is used to determine the known amount forcomparison with the next stable amplitude. Signal 50 is shown droppingand then rising to a third amplitude that is stable for the minimum timeperiod Tstable at point 310. The third amplitude exceeds the secondamplitude by more than the known amount K_(vb)×Cbase such that anactivation output for the switch is generated.

Referring to FIG. 24, another example of a signal 50 is illustratedentering the exploration mode at point 300 and continuing to rise to afirst amplitude that is stable for a minimum time period Tstable atpoint 302 in which the virtual button mode is entered and Cbase isdetermined. Thereafter, the signal 50 is shown dropping to a secondamplitude that is stable for the minimum time period Tstable at point312. At point 312, the second amplitude does not exceed the firstamplitude by the known amount of K_(vb)×Cbase such that a trigger of thesignal is not generated. However, an updated base value Cbase isgenerated at point 312. Thereafter, signal 50 continues to rise to athird amplitude that is stable for the minimum time period Tstable atpoint 310. The third amplitude exceeds the second amplitude by the knownamount K_(vb)×Cbase, such that a trigger or activation output for theswitch is generated.

Referring to FIG. 25, another example of a signal 50 for a signalchannel is shown entering the exploration mode at point 300 andproceeding to reach a first amplitude that is stable for the minimumtime period Tstable at point 302 and therefore enters the virtual buttonmode and determines Cbase. Next, signal 50 continues to rise to a secondamplitude that is stable for the time period Tstable at point 308. Thesecond amplitude does not exceed the first amplitude by the known amountsuch that a trigger of the switch is not generated at this point.Thereafter, signal 50 is shown dropping to point 314 and in the processof doing so, a reset timer times out since the last stable amplitude wasreceived as shown by time Treset. When the reset timer times out, atpoint 314, the virtual button mode is exited and the exploration mode isentered once the virtual button mode is exited. When this occurs, theprior determined Cbase is no longer valid. Thereafter, signal 50 isshown rising to a third amplitude that is stable for the minimum timeperiod Tstable at point 316. At this point, the third amplitudeestablishes an updated Cbase which is used for determining futureactivations of the switch. Thereafter, the signal 50 is further showndropping below the threshold active value 320, in which case, thevirtual button mode is exited without any activations.

A method of activating a proximity switch with a virtual button modeusing the proximity switch assembly is illustrated in FIGS. 26 and 27.Referring to FIG. 26, method 400 begins at step 402 and proceeds toacquire all signal channels associated with all proximity switches atstep 404. Method 400 proceeds to decision block 406 to determine if thestate is set in the ACTIVE state and, if so, checks for a release of theswitch at step 414 before ending at step 416. If the state is not set tothe ACTIVE state, method 400 proceeds to step 408 to find the maximumchannel (CHT). Next, once the maximum channel has been found, routine400 proceeds to step 410 to process the maximum channel (CHT)virtual-button method before ending at step 416. The process maximumchannel virtual-button method 410 is illustrated in FIG. 27 anddescribed below. It should be appreciated that method 400 may include anoptional step 412 for also processing the maximum channel signal using atapping method to detect a user tapping on a proximity switch so as togenerate an activation output.

The process maximum channel virtual-button method 410 shown in FIG. 27begins at step 420 and proceeds to step 422 to input the maximum channelsignal. Hence, the maximum signal channel associated with one of theproximity switches is processed to determine the virtual button modestate and activation of the switch. At decision step 424, method 410determines if the switch is set to the virtual button mode state and, ifso, proceeds to decision step 426 to determine if the signal channelvalue is less than the active threshold. If the signal channel is lessthan the active threshold, method 410 proceeds to step 428 to set thestate equal to NONE and returns to the beginning. If the signal channelis not less than the active threshold value, method 410 proceeds todecision step 430 to determine if the signal has a stable firstamplitude for a time period greater than the stable time period Tstable.If the stable signal channel at the first amplitude is stable for a timeperiod greater than Tstable, method 410 proceeds to decision step 432 todetermine if the signal channel is not stable for a time periodexceeding the reset time period Treset and, if not, returns to step 422.If the signal channel is not stable for a time period exceeding thereset time period Treset, method 410 proceeds to set the state equal tothe exploration/hunting state and ends at step 460.

Returning to decision step 430, if the signal channel is stable for atime period exceeding the stable time period Tstable, method 410proceeds to decision step 436 to determine if the signal Ch(t) isgreater than Cbase by a known amount defined by K_(vb)×C_(base) and, ifso, sets the switch state to active so as to generate an activationoutput before ending at step 460. If the signal does not exceed Cbase bythe known amount of K_(vb)×C_(base), method 410 proceeds to set the newCbase value at the current stable signal amplitude at step 440, beforeending at step 460.

Returning to decision step 424, if the switch state is not set to thevirtual button mode, method 410 proceeds to decision step 442 todetermine if the state is set to the exploration state and, if so,proceeds to decision step 444 to determine if the signal is greater thanthe active threshold and, if not, sets the state equal to the NONE stateand ends at step 460. If the signal is greater than the activethreshold, method 410 proceeds to decision step 448 to determine if thesignal is stable at an amplitude for a time period exceeding the minimumtime period Tstable and, if not, ends at step 460. If the signal isstable at an amplitude for a time period exceeding the minimum timeperiod Tstable, method 410 proceeds to step 450 to set the state for theswitch to the virtual button state and to establish the new Cbase valuefor the signal channel at step 450 before ending at step 460.

Returning to decision step 442, if the state of the switch is not set tothe exploration/hunting state, method 410 proceeds to decision step 452to determine if the signal is greater than the active threshold and, ifnot, ends at step 460. If the signal is greater than the activethreshold, method 410 proceeds to decision step 454 to set the state tothe exploration/hunting state before ending at step 460.

Accordingly, the proximity switch assembly having the virtual buttonmethod 410 advantageously provides for enhanced virtual button switchactivation detection and improved rejection of unintended activations.Method 410 may advantageously detect an activation of a switch whilerejecting unintended activations which may be detected when a fingerexplores the switch assembly and reverses direction or in which theuser's finger is wearing a glove. The enhanced activation detectionadvantageously provides for enhanced proximity switch assembly.

Accordingly, the determination routine advantageously determinesactivation of the proximity switches. The routine advantageously allowsfor a user to explore the proximity switch pads which can beparticularly useful in an automotive application where driverdistraction can be avoided.

The proximity switch assembly 20 may include a pliable materialoverlaying the proximity sensor and the control circuitry may activate aproximity switch based on a signal generated by the sensor in relationto a threshold when a user's finger depresses the pliable material,according to a further embodiment. In this embodiment, the proximityswitch assembly 20 may operate in the virtual button mode and mayprovide enhanced signal detection by employing the pliable materialwhich deforms to allow the user's finger to move closer to the proximitysensor. In addition, a void space in the form of an air pocket may beprovided between the pliable material and the proximity sensor and araised or elevated surface may further be provided in the pliablematerial.

Referring to FIGS. 28A-31, the proximity switch assembly 20 employingthe pliable material and operating in a virtual button mode and a methodof activating the proximity switch with the use of the pliable materialin the virtual button mode is shown therein, according to thisembodiment. The proximity switch assembly 22 may include a proximitysensor, such as a capacitive sensor, generating an activation field. Itshould be appreciated that a plurality of proximity sensors 24 eachgenerating an activation field may be employed. The proximity sensors 24are shown provided on the surface of a rigid substrate, such as apolymeric overhead console 12, according to one embodiment. Each of theproximity sensors 24 may be formed by printing conductive ink onto thesurface of the polymeric overhead console 12. The proximity sensors 24may otherwise be formed such as by assembling preformed conductivecircuit traces onto a substrate according to other embodiments.

A pliable material 500 is shown covering the substrate 12 and isintended to provide the touch surface for a user's finger 34 to interactwith proximity sensors 24 to activate the switches 22. The pliablematerial 500 is shown formed as a cover layer which may be made of anelastic material including rubber, according to one embodiment. Thepliable material 500 is flexible relative to the underlying substrate 12which is generally rigid. The pliable material 500 overlays theproximity sensor 24 and is deformable when a user's finger 34 appliespressure such that the finger 34 compresses the pliable material 500 andmoves inward toward the proximity sensor 24 as shown in FIG. 28C.According to one embodiment, the pliable material 500 may have a layerthickness in the range of approximately 0.1 to 10 millimeters, and morepreferably in the range of 1.0 to 2.0 mm.

The proximity switch assembly 20 employs control circuitry formonitoring the activation field associated with each sensor 24 anddetermining an activation of a proximity switch based on a signalgenerated by the proximity sensor 24 in relation to a threshold when auser's finger 34 depresses the pliable material 50. The controlcircuitry may determine a stable amplitude of a signal generated by theproximity sensor 24 for a predetermined time period and may generate aswitch activation output when the stable output exceeds a thresholdvalue. According to one embodiment, the control circuitry may determinea first stable amplitude of a signal for a time period, may determine asubsequent second stable amplitude of the signal for a time period, andmay generate an activation output for a proximity switch associated withthe signal when the second stable signal exceeds the first stable signalby a known amount.

Referring to FIGS. 28A-28D, the proximity switch assembly 20 isillustrated employing a pliable material 500 overlaying one or moreproximity sensors 24, according to a first embodiment. As seen in FIG.28A, a user's finger 34 shown in a first position contacts the surfaceof the pliable material 500 at a location close to but laterallydisplaced from a proximity sensor 24. In FIG. 28B, the user's finger 34is shown moving by sliding laterally to a second position aligned with aproximity sensor 24 without applying pressure to the pliable material500. This may occur when a user is exploring the proximity sensorassembly 20 in an exploration/hunting mode without an intent to activatethe switch 22. In FIG. 28C, the user's finger 34 is shown applying aforce toward the proximity sensor 24 so as to depress the pliablematerial 500 to move the user's finger 34 to a third position closer tothe proximity sensor 24. The user's finger 34 may thereby press onto anddeform the pliable material 500 to move closer to the proximity sensor24 and may further squish and thereby flatten the finger 34 against thesubstrate 12 to provide an enhanced surface area or volume of the fingerin close proximity to the sensor 24 which provides greater interactionwith the associated activation field and hence, a greater signal.

The sequence of events shown in FIGS. 28A-28C are further illustrated inthe signal response shown in FIG. 28D. The signal 506 generated by theproximity sensor 24 is shown rising up to a first level 506A indicativeof the user's finger 34 in contact with the proximity switch assembly 20at the first position laterally distant from the proximity sensor 24 asseen in FIG. 28A. The signal 506 then rises to level 506B indicative ofthe user's finger 34 shown in the second position aligned with theproximity sensor 24 without applying force as shown in FIG. 28B.Thereafter, signal 506 then rises to a third elevated level 506Cindicative of the user's finger 34 applying force in the third positionto depress the pliable material 500 as shown in FIG. 28C. Thus, thesignal 506 is much greater when the user's finger 34 depresses into thepliable material 500 which enables virtual button detection.

The control circuitry monitors the activation field and determines anactivation of the proximity switch based on signal 506 in relation to athreshold when the user's finger presses the pliable material 500. Theprocess circuitry may include the controller 400 shown in FIG. 5 forexecuting a control routine which may include routine 520 shown anddescribed herein in connection with FIG. 31. As such, the processcircuitry may use a virtual button method as described above to detectan exploration mode and virtual button activations of one or moreproximity switches.

The proximity switch assembly 20 may further be configured with apliable material 500 having a raised or elevated touch surface portion502 aligned with each proximity sensor 24 and a void space or air gap504 disposed between the elevated portion 502 and the proximity sensor24 as shown in FIGS. 24A-24C, according to another embodiment. In thisembodiment, the air gap 504 formed between the pliable material 500 andeach proximity sensor 24 provides an enhanced distance of travel duringswitch activation that may also serve as a haptic feel for a user. Theair gap 504 may have a height distance of less than 5.0 millimeters,according to one embodiment, more preferably in the range of 1.0 to 2.0millimeters. The elevated portion 502 of pliable material 500 keeps theuser's finger 34 more distal from the proximity sensor 24 in theundepressed state. As shown in FIG. 29A, a user's finger 34 contacts theproximity switch assembly 20 at a location close to but laterallydistanced from the proximity sensor 24 in a first position. Next, atFIG. 28B, the user's finger 34 moves to a second position aligned withthe proximity sensor 24 on top of the elevated portion 52 of pliablematerial 500. In this position, a user's finger 34 may be exploring theproximity switches 22 in an exploration/hunting mode, without any intentto activate a switch. In FIG. 29C, the user's finger 34 is shown in athird position depressing the pliable material 500 on top of theelevated portion 502 so as to move the finger 34 to a fully depressedstate that compresses the pliable material 500 and the air gap 504 toallow the user's finger to be in a closer position relative to theproximity sensor 24. When this occurs, the control circuitry detects anintent of the user to activate the switch 22 and generates an activationoutput signal.

Referring to FIG. 28D, the signal 506 generated in response toactivation of the activation field by the proximity sensor 24 is shownin relation to the user's finger actuations shown in FIGS. 29A-29C.Signal 506 is shown rising up to a first level 506A indicative of theuser's finger 34 in the first position contacting the proximity switchassembly 20 at a lateral distance away from the sensor 24 shown in FIG.29A. Signal 506 remains at the first level 506A as shown also by level506B while the user's finger rises up to the second position on theelevated portion 502 aligned above proximity sensor 24 withoutdepressing pliable material 500 as shown in FIG. 29B. The elevatedportion 502 thereby allows the signal 506 to maintain a low signal whena user's finger is in an exploration mode and is not intending toactivate the switch 22. The signal 506 is shown increasing to a furtherelevated level 506C indicative of the user's finger 34 depressing thepliable material in the third position by compressing the elevatedportion 502 and air gap 504 as shown in FIG. 29C to activate the switch22. The control circuitry processes the signal 506 to detect anactivation of the switch 22 when this occurs, and may further detect anexploration/hunting mode as described above.

Referring to FIG. 30, a state diagram is shown for the proximity switchassembly in another state machine implementation that utilizes thepliable material and virtual button mode, according to one embodiment.The state machine implementation is shown having four states includingthe wait state 510, the hunting state 512, the virtual button state 514and the button press state 516. The wait state 510 is entered when thesignal is less than a threshold indicative that there is no sensoractivity detected. The hunting state 512 is entered when the signal isgreater than a threshold indicative of activity determined to becompatible with an exploration/hunting interaction. The virtual buttonstate 514 is entered when the signal is stable. The button press state516 is indicative of a forceful press on the switch to compress thepliable material once in the virtual button state. When the signalreaches a certain threshold, the hunting/exploration mode 512 isentered. When the signal is stable and greater than a base level, thevirtual button mode 514 is entered. If the signal is stable and greaterthan a base level plus a delta dome value, the button press mode 516 isentered. It should be appreciated that the base level may be updated asdescribed above.

Referring to FIG. 31, the routine 520 for controlling the proximityswitch assembly and method of activation using a pliable material asdescribed above in connection with FIGS. 28A-30 is shown and describedherein. Routine 520 may be stored in memory 48 and executed bycontroller 40, according to one embodiment. Routine 520 begins at step522 to process the largest or maximum signal channel, which is themaximum signal channel associated with one of the proximity switches. Atstep 524, the maximum signal channel is input to the controller. Next,at decision step 526, routine 520 determines if the current state is setto the wait state and, if so, proceeds to decision step 528 to determineif the maximum signal channel is greater than a threshold. If themaximum signal channel is not greater than the threshold, routine 520ends at step 530. If the maximum signal channel is greater than athreshold, routine 520 proceeds to set the state to the hunting state atstep 532 before ending at step 530.

Returning to decision step 526, if the state is set to the wait state,routine 520 proceeds to decision step 534 to determine if the state isset to the hunting state and, if so, proceeds to decision step 536 todetermine if the maximum signal channel is less than a threshold. If themaximum signal channel is less than the threshold, routine 520 proceedsto step 538 to set the state to the wait state, and then ends at step530. If the maximum signal channel is not less than the threshold 536,routine 520 proceeds to decision step 540 to determine if all signalchannels are stable and, if not, ends at step 530. If all signalchannels are stable, routine 520 proceeds to step 542 to set the stateequal to the virtual button state, and thereafter sets the channel baseto the maximum signal channel at step 544 before ending at step 530.

Returning to decision step 534, if the state is not set equal to thehunting state, routine 520 proceeds to decision step 546 to determine ifthe state is in the virtual button state and, if not, proceeds to step548 to set the state to the button press state. Thereafter, routine 520proceeds to decision step 550 to determine if the maximum signal channelis less than a threshold and, if not, ends at step 530. If the maximumchannel is less than a threshold, routine 520 sets the state equal tothe wait state at step 552 and then releases activation at step 554before ending at step 530.

Returning to decision step 546, if the state is set equal to the virtualbutton state, routine 520 proceeds to decision step 556 to determine ifthe maximum signal channel is less than a threshold and, if so, sets thestate equal to the wait state at step 558 before ending at step 530. Ifthe maximum signal channel is not less than the threshold, routine 520proceeds to decision step 560 to determine if the virtual button timeris greater than a timeout and, if so, sets the state to the huntingstate at step 562 before ending at step 530. The virtual button timermay be set to a range of one to three seconds, according to oneembodiment. If the virtual button timer has not exceeded the timeout,routine 520 proceeds to decision 564 to determine if all signal channelsare stable and, if not, ends at step 530. If all signal channels aredetermined to be stable, routine 520 proceeds to decision step 566 todetermine if the rubber dome is depressed which may be determined by themaximum signal channel greater than a signal channel base summed with asignal delta dome value. If the rubber dome is depressed, routine 520proceeds to decision step 568 to set the state equal to the button pressstate, and thereafter generates an activation of the maximum signalchannel at step 570 before ending at step 530. If the rubber dome is notdepressed, routine 520 proceeds to step 572 to determine that the fingeris still sliding and to update the base signal ChBase to the maximumsignal channel at step 572 before ending at step 530.

Accordingly, proximity switch assembly 20 having the pliable material500 and virtual button mode advantageously provides for enhanced virtualbutton switch activation detection to improve the rejection ofunintended activations. Method 520 may advantageously detect anactivation of a switch while rejecting unintended activation switch maybe detected when a finger explores the switch assembly. The enhancedactivation detection advantageously provides for enhanced proximityswitch assembly which can be particularly advantageous or useful in anautomotive application where a driver distraction may be avoided.

The proximity switch assembly 20 may include a rigid substrate having afirst top surface and a second bottom surface, a proximity sensordisposed on the substrate, a pliable material disposed on the topsurface of the substrate, and a depression formed within the top surfaceof the substrate in a region between the pliable material and theproximity sensor, according to one embodiment. The depression isgenerally larger in size than the proximity sensor such that thedepression has a longer length and width as compared to the proximitysensor. The depression allows for the formation of an air gap betweenthe pliable material and the proximity sensor.

Referring to FIGS. 32-34D, the proximity switch assembly 20 employing apliable material 500 overlaying a rigid substrate 12, and depressions600 formed within a top surface of the substrate 12 is illustratedaccording to one embodiment. The proximity switch assembly 20 includesthe rigid substrate 12 generally shown as a planar sheet having firstand second surfaces shown as top and bottom surfaces. First and secondproximity sensors 24, such as capacitive sensors, are shown disposed onthe bottom surface of the substrate 12, each of which generates anactivation field for a corresponding proximity switch 22. It should beappreciated that one or a plurality of proximity sensors 24 may beincluded, each sensor generating an activation field. The proximitysensors 24 are shown provided on the bottom surface of the rigidsubstrate 12, such as a polymeric overhead console 12, according to oneembodiment. Each of the proximity sensors 24 may be formed by printingconductive ink onto the bottom surface of the rigid substrate 12. Theproximity sensors 24 may otherwise be formed such as by assemblingpreformed conductive circuit traces onto the substrate 12 according toother embodiments.

A pliable material 500 is shown covering the substrate 12 and isintended to provide the touch surface for a user's finger 34 to interactwith one or more of the proximity sensors 24 to activate one or more ofthe proximity switches 22. The pliable material 500 may be formed as acover layer which may be made of an elastic material including rubber,according to one embodiment. The pliable material 500 is flexiblerelative to the underlying substrate 12 which is generally rigid. Thepliable material 500 overlays the proximity sensors 24 and is deformablewhen a user's finger applies pressure such that the finger 34 compressesthe pliable material 500 and moves toward a proximity sensor 24. Thepliable material 500 may have a thickness as described above inconnection with other embodiments, such as in the range of 0.1 to 10millimeters, and more preferably in the range of 1.0 to 2.0 millimeters.

The proximity switch assembly 20 further includes a depression 600within the top surface of the rigid substrate 12 in a region between thepliable material 500 and each proximity sensor 24. Separate depressions600 may be formed in the top surface of the substrate 12, each generallyproximate one of the proximity sensors 24. The depression 600 has alength and width that is larger in size than the proximity sensor 24.The relative size of the depression 600 relative to the proximity sensor24 is illustrated in FIG. 33. The depression 600 has a first lengthL_(D) as compared to the proximity sensor 24 which has a second lengthL_(S), wherein the first length L_(D) is greater than the second lengthL_(S) by at least 5 millimeters, according to one embodiment. Accordingto a more specific embodiment, the first length L_(D) exceeds the secondlength L_(S) by a distance in the range of 5 to 10 millimeters. Thedepression 600 also has a width W_(D) that is larger than a width W_(S)of the proximity sensor 24. The width W_(D) may exceed the width W_(S)by an amount of at least 5 millimeters, according to one embodiment, andmore specifically by a distance in the range of 5 to 10 millimeters. Thedepression 600 may have a thickness in the range of 0.5 to 2.0millimeters according to one embodiment.

While the proximity switch assembly 20 is shown and described hereinhaving each proximity sensor 24 and depression 600 formed in arectangular shape, it should be appreciated that the sensor 24 anddepression 600 may include other shapes and sizes, such as a circularshape or other shape. In doing so, the depression 600 has a depth andalso has a size dimension of length and/or width that is greater than alength and/or width dimension of the proximity sensor 24 proximatethereto. For a circular shaped proximity sensor 24 and depression 600,the dimension may be a length measurement of the diameter of thecircular shape for each of the sensor 24 and depression 600, wherein thedimension of the depression 600 is greater than the dimension of theproximity sensor 24 by an amount of at least 5 millimeters, according toone embodiment, more specifically in the range of 5 to 10 millimeters.

According to one embodiment, the depression 600 formed in the rigidsubstrate 12 provides a space for an air gap to be formed between thebottom surface of the depression 600 of substrate 12 and the overlayingpliable material 500. The air gap formed within depression 600 providesa space for the user's finger to depress the pliable material 500 inwardand into close proximity with the proximity sensor 24. While an air gapis shown and described herein as filling the void space withindepression 600, it should be appreciated that another material, such asa liquid or other gas may be disposed therein. It should further beappreciated that a soft pliable material may be disposed within thedepression 600, with the material being substantially less rigid thanthe rigid substrate 12.

The proximity switch assembly 20 may further employ control circuitryfor monitoring the activation field associated with each proximitysensor 24 and determining an activation of a corresponding proximityswitch 22 based on a signal generated by the proximity sensor 24 inrelation to a threshold when a user's finger 34 depresses the pliablematerial 500 into depression 600. The signal generally increases inamplitude when the user's finger moves closer to the proximity sensor24. The control circuitry may operate as described above in connectionwith the embodiments shown in FIGS. 28A-31.

Referring to FIGS. 34A-34D, the proximity switch assembly 20 isillustrated employing the pliable material 500 overlaying a depression600 above each of proximity sensors 24, according to a first embodiment.As seen in FIG. 34A, a user's finger 34 is shown in a first positioncontacting the top surface of the pliable material 500 at a locationclose to but laterally displaced from a proximity sensor 24 anddepression 600. In FIG. 34B, the user's finger 34 is shown moving bysliding laterally to a second position aligned centrally above aproximity sensor 24 and depression 600 without applying force orpressure to the pliable material 500. This may occur when a user isexploring the proximity sensor assembly 20 in an exploration/huntingmode without any intent to activate the proximity switch 22. In FIG.34C, the user's finger 34 is shown applying a force towards theproximity sensor 24 so as to depress the pliable material 500 to movethe user's finger 34 to a third position closer to the proximity sensor24 so as to compress the pliable material 500 and collapse the air gapprovided within depression 600, and may further squish and therebyflatten the finger against the substrate 12 within the bottom of thedepression 600 to provide an enhanced surface area or volume of thefinger in close proximity to the sensor 24 which provides greaterinteraction with the associated activation field and hence, a greatersignal.

The sequence of events shown in FIGS. 34A-34C are further illustrated inthe signal 606 response shown in FIG. 34D. The signal 606 generated bythe proximity switch 24 is shown rising up to a first level 606Aindicative of the user's finger 34 in contact with the proximity switchassembly 20 at the first position laterally distant from the proximitysensor 24 as seen in FIG. 34A. The signal 606 maintains a signalamplitude at level 606B indicative of the user's finger 34 shown in thesecond position aligned with the proximity sensor 24 and depression 600without applying force as shown in FIG. 34B. Thereafter, signal 606 thenrises to a third elevated level 606C indicative of the user's fingerapplying force in the third position to depress the pliable material 500into depression 600 as shown in FIG. 34C. Thus, the signal 606 is muchgreater when the user's finger 34 depresses the pliable material 500into depression 600 which enables enhanced switch detection. The controlcircuitry may then monitor the activation field and the signal 606 anddetermine activation of the proximity switch 22 based on signal 606 asdescribed herein.

The proximity switch assembly 20 may be configured with one or moregrooves formed in the rigid substrate between first and second proximitysensors as shown in FIGS. 35-37E, according to another embodiment. Inthis embodiment, a single groove 610 is shown disposed between adjacentproximity sensors 24 to provide signal isolation between the adjacentproximity sensors 24. It should be appreciated that one or a pluralityof grooves may be formed in the rigid substrate 12 between the adjacentproximity sensors 24. In this embodiment, the groove 610 may be employedin combination with depressions 600 or may be employed absent thedepressions 600. By employing a combination of depressions 600 andgroove 610, enhanced signal detection and reduced signal interferencemay be achieved. By employing groove 610 without depressions 600, a morecompact proximity switch assembly 20 may be achieved with proximityswitches 22 located close together without the enlarged sizedepressions.

As seen in FIGS. 35 and 36, the groove 610 is shown formed in the topsurface of the rigid substrate 12 in a region between first and secondproximity sensors 24. The groove 610 may have a first dimension shown aslength L_(G) that is at least as long as W_(S) the width of the sensor24, or at least as long as W_(D) in the embodiment with depression 600,and, preferably 5 to 10 millimeters longer than width W_(S) or 0 to 5millimeters longer than width W_(D) in the embodiment with depression600, and a second dimension shown as width W_(G) in the range of 1millimeter to 5 millimeters. The depth of the groove 610 may be in therange of 0.5 to 2.0 millimeters. It should be appreciated that the depthof the groove 610 may extend a substantial distance into the top surfaceof the rigid substrate 12. In one embodiment, the rigid substrate 12 ismade of plastic. The groove 610 forms an air gap therein. The air gaphas a low dielectric which effectively reduces the activation field inthat region and reduces or prevents signal cross talk or interference.

Referring to FIGS. 37A-37E, the proximity switch assembly 20 isillustrated employing the pliable material 500, depressions 600 andgroove 610, according to one embodiment. As seen in FIG. 37A, a user'sfinger 34 shown in a first position contacts a surface of the pliablematerial 500 at a location close to but laterally displaced from aproximity sensor 24. In FIG. 37B, the user's finger 34 is shown movingby sliding laterally to a second position aligned with a first proximitysensor 24 without applying force or pressure to the pliable material500. This may occur when a user is exploring the proximity sensorassembly 20 in an exploration/hunting mode without an intent to activatethe proximity switch 22. In FIG. 37C, the user's finger 34 is shownmoving by sliding laterally over the groove 610 to a third positionaligned with a second proximity sensor without applying force orpressure to the pliable material 500, such as may occur in theexploration/hunting mode. In FIG. 37D, the user's finger 34 is shownfurther sliding to a fourth position in the region of the secondproximity sensor 34. It should be appreciated that a user may depressthe pliable material 500 above either of the first or second proximitysensors 24 so as to activate either the first or second proximityswitches 22.

The sequence of events shown in FIGS. 37A-37D are further illustrated inthe first and second signals 608 and 609 responses shown in FIG. 37E.The first signal 608 generated by the first proximity sensor 24 is shownat a first level 608A, when the user's finger is in contact with theproximity switch assembly 20 at both the first and second positions asseen in FIGS. 37A and 37B. As the user's finger approaches the groove610 between the first and second proximity sensor, the first signal 608drops to a reduced or zero value. A second signal 609 generated by thesecond proximity sensor 24 rises back up to signal level 608C and 608Dwhen the user's finger moves away from groove 610 and approaches thethird and fourth positions as shown in FIGS. 37C and 37D. The effect ofthe signals 608 and 609 being at a reduced or zero value occurs when theuser's finger 34 passes over the groove 610 between the first and secondproximity sensors 24. The groove 610 effectively isolates the signals608 and 609 to reduce the signal values to a lower or zero value andthereby prevents interference between adjacent proximity sensors 24. Thecontrol circuitry may thereby determine activation of either the firstand second switches 22 based on signals 608 and 609 with reduced signalinterference.

The proximity switch assembly 20 is further illustrated configured witha pliable material 500 having a raised or elevated touch surface portion620 aligned with each of proximity sensors 24 and depressions 500 asshown in FIG. 38, according to a further embodiment. In this embodiment,the elevated surface 620 provides an enhanced distance of travel betweenswitch activations that may also serve as a haptic feel for a user. Theheight of the elevated surface 620 may be in the range of 1 to 2millimeters, according to one embodiment. The elevated surface 620 maykeep the user's finger 34 more distal from the proximity sensor in theundepressed state. It should further be appreciated that the elevatedsurface 620 may be employed with the depressions 600 or with one or moregrooves 610, or with both the depressions 600 and one or more grooves610.

Accordingly, the proximity switch assembly 20 having the pliablematerial 500 may employ depressions 600 and/or one or more grooves 610to provide for enhanced signal detection and switch activation.

It is to be understood that variations and modifications can be made onthe aforementioned structure without departing from the concepts of thepresent invention, and further it is to be understood that such conceptsare intended to be covered by the following claims unless these claimsby their language expressly state otherwise.

What is claimed is:
 1. A proximity switch assembly comprising: a rigidsubstrate having top and bottom surfaces; a proximity sensor disposed onthe substrate; a pliable material disposed on the top surface of thesubstrate; and a depression within the top surface of the substrate in aregion between the pliable material and the proxy sensor, wherein thedepression is larger than the proximity sensor.
 2. The proximity switchassembly of claim 1, wherein the depression has a first length and theproximity sensor has a second length, wherein the first length isgreater than the second length by at least 5 millimeters.
 3. Theproximity switch assembly of claim 2, wherein the first length exceedsthe second length in the range of 5 to 10 millimeters.
 4. The proximityswitch assembly of claim 1, wherein the depression has a thickness inthe range of 0.5 to 2.0 millimeters.
 5. The proximity switch assembly ofclaim 1, wherein the pliable material is rubber.
 6. The proximity switchassembly of claim 1, wherein an air gap is formed within the depression.7. The proximity switch assembly of claim 1, wherein the proximitysensor is disposed on the bottom surface of the substrate.
 8. Theproximity switch assembly of claim 1 further comprising controlcircuitry monitoring an activation field associated with the proximitysensor and determining an activation of the proximity switch based on asignal generated by the sensor in relation to a threshold when a user'sfinger depresses the pliable material.
 9. The proximity switch assemblyof claim 1, wherein the assembly comprises a plurality of proximityswitches, each of the proximity switches comprising a proximity sensorformed on the bottom surface of the substrate and a depression formed onthe top surface of the substrate, and at least one groove extending intothe substrate between adjacent proximity switches.
 10. The proximityswitch assembly of claim 1, wherein the proximity switch assemblycomprises a capacitive switch comprising one or more capacitive sensors.11. The proximity switch assembly of claim 1, wherein the assembly isinstalled on a vehicle.
 12. The proximity switch assembly of claim 1,wherein the pliable material comprises an elevated portion disposed overthe depression.
 13. A vehicle proximity switch assembly comprising: arigid substrate having first and second surfaces; a proximity sensordisposed on the first surface of the substrate; a pliable materialdisposed on the second surface of the substrate; and a depressionforming an air gap within the second surface of the substrate in aregion between the pliable material and the proximity sensor, whereinthe depression is longer than the proximity sensor.
 14. The vehicleproximity switch assembly of claim 13, wherein the depression has afirst length and the proximity sensor has a second length, wherein thefirst length is greater than the second length by at least 5millimeters.
 15. The vehicle proximity switch assembly of claim 14,wherein the first length exceeds the second length in the range of 5 to10 millimeters.
 16. The vehicle proximity switch assembly of claim 13,wherein the depression has a thickness in the range of 0.5 to 2.0millimeters.
 17. The vehicle proximity switch assembly of claim 13,wherein the pliable material is rubber.
 18. The vehicle proximity switchassembly of claim 13, wherein the proximity switch comprises acapacitive switch comprising one or more capacitive sensors.
 19. Theproximity switch assembly of claim 13, wherein the pliable materialcomprises an elevated portion disposed over the depression.
 20. Theproximity switch assembly of claim 13, wherein the assembly comprises aplurality of proximity switches, each of the proximity switchescomprising a proximity sensor formed on the bottom surface of thesubstrate and a depression formed on the top surface of the substrate,and at least one groove extending into the substrate between adjacentproximity switches.